Many wireless communication systems use communication stations (base stations, eNodeBs, eNBs) to provide geographical service areas where wireless communication user equipment devices (UE devices) communicate with the communication station providing the particular geographical service area in which the UE devices are located. The communication stations are connected within a network allowing communication links to be made between the wireless communication devices and other devices. The communication system may include communication stations that provide overlapping service areas of different sizes to serve various needs of mobile UE devices. For example, macrocell communications stations may provide macrocell service areas that are larger and may cover one or more small cell service areas provided by small cell communication stations.
In some circumstances, the communication links are between wireless communication UE devices that are close to each other. In these situations, it may be preferred to have a direct communication link between the two wireless UE devices rather than communicating through a base station. Such direct communication between devices is often referred to as device-to-device (D2D) communication or peer-to-peer (P2P) communication. D2D discovery signals are transmitted to allow D2D mobile devices to discover other D2D mobile devices that may be candidates for D2D communication. The discovery signals are transmitted at times and frequencies typically designated by a communication specification.